83 300D turbo here as well, with the same exact vaccum issue and the same exact problem with the HVAC. Dont tell me your engine shakes like a paint shaker on hot idle and your rear sway bar end links are busted? That would be ironic. Does it sound like you have dead bodies bouncing around in the trunk?

^ a hot shaking is usually the rack damper bolt/pin that needs adjusting or replacing.

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83 SD

84 CD

LOL. No dead bodies, but the day is young and the list is long.

No shaking at hot idle. Well, I shouldn't say no shaking. Usually not, but sometimes yes and only very slight.

I think my Climate Control Unit is dead, but haven't had time to troubleshoot it. Been dealing with a faulty gauge cluster. Since it's summer, I'll wait until august or so to worry about that.

Here's a summary of what I did to the vacuum lines under the hood. I'll refer to the schematic attached above.

1. Remove all lines from #71 (Central Plug)
2. Remove the Black line (bk) from the "T" connector that comes off the bottom of #65 (Vacuum Contol Valve or VCC) and goes to 71.
3. Replace the "T" connector at same spot with a straight line that connects the VCC to the black vent line (a). This vent line travles through the firewall and into the cabin and is, apparently, not connected to anything. (see post above)
4. Remove "T" connector between orrifices 62 and 63 and replace with a straight line connecting 62 to 63. This eliminates that white (wh) line going to 71.
5. Remove all lines going to 36a and 60 and plug the ports left behind on 36a and 60. You can get vacuum plugs at any auto parts store for less than $3.

This process made my trans act like new. No hard shifting at all. And, as an added bonus, you get some spare vacuum lines and connectors.

The other thing I did, that helped boost my power, is connect the ALDA again. There are two connections. Both lead to a device mounted on the firewall (can't remember what it's called) The ALDA goes in the port that sticks out the front and the second line goes from the Intake Manifold (drivers side, back of engine) to the port that sticks out of the bottom. You may have to take this thing off the firewall to hook it up. I got lucky and was able to connect it without doing that. I got a huge boost in power. Drives like a gasser now. I have also heard of folk going directly from the manifold to the ALDA. Don't know much about that so you may want to poke around to find more info.

Hope that helps

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Troy

1983 300D Turbo
1981 240D

Troy,

I just bought my 83 300D about a month ago. Paid too much for it but its rust free and in really good cosmetic condition.

what gauges are you having problems with? My tachometer dosnt work. My friend's 300D does work, so i swapped out the tach amps. Mine still didnt. I did get to verify that my tach amp works fine. So i guess i need to check the gauge itself or the rpm sensor (if i can figure out where the heck that thing is).

Also, my odometer has stripped gears. It works intermittently so who knows how many true miles my car has. (shows 151k)

I have the same climate control issue as you. I dont know if its the unit or leaky pods.

Same vaccum problem. As soon as i get a chance i will do exactly what you did. I have harsh shifting and sometimes it changes gears too fast. It dosnt like to kick down right either so eventually ill play with the kickdown/bowden cable

I did take a piece of tin can and make a blank gasket to block off the EGR valve so exhaust pressure wouldnt open it and keep gunking up my intake. Did you consider doing this?

Have you adjusted your valves yet? Mine is long overdue and i believe some of my engine shake at hot idle has to do with that. First im going to adjust the valves, solve the vaccum issue, replace the rack damper bolt if the shaking isnt gone, and then worry about the climate control.

My buddy has an 82 300D and we did a diesel purge on both cars. Liqui molly is impossible to find here in Illinois, so we just used 2 cans of seafoam each and mixed in some ATF. We took the main fuel line and return line and ran them into a half gallon mason jar with holes drilled in the lid. Took them out and drove them till they almost ran out, dumped out the cruddy stuff and filled the jars with a can of clean diesel to get back home and change the lines back and change fuel filters.

My cars system was pretty clean as it didnt change the color of the liquid but oh man, my buddys car turned the jar of liquid to a dark black sludge. She was filthy. Could definitely tell a difference after the purge on his car.

When you hooked up your alda, did you clean the banjo bolt on the back of the intake? I did this and it did wonders. Both cars were completely plugged with black crust. I bypassed the valve on the firewall and ran it straight from the banjo bolt to the alda.

What else have you ran into on yours?

My aux fan has a switch wired to it so you can kick it on via the dash. I cant get the ac compressor to come on. The cruise control dosnt work. etc etc

Im still falling in love with this car though. Shes a head turner

Make sure all your fuses are good, by that, I mean to remove and inspect each end.
The pic shows the tach sensor cable, the number is on the bottom.
Harsh shifting is usually too little or no vacuum getting to the modulator.
Cruise control failures are quite routine, usually the amp no longer works.

Attached Thumbnails

 

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83 SD

84 CD

Got around to getting rid of all the EGR vaccum crap. I just used small bolts in the tee's to plug them. Took it on a few mile test drive and she seemed to shift a LOT better. No longer wants to chirp the tires going into second or throw gravel when it shifts. Big relief, thanks for your help guys.

usually if the center vents do not work it is the center pods behind the vents that dont work, those pods actuate the opening of the vents.
If you do a search in the forum google search you should be able to find some real good pictures
I do much better with pictures. Keep us posted so we can learn from you too.

I think its the climate control unit itself. I read somewhere that it defaults to just the side vents and defroster, and no matter what i set it to it dosnt change. I somehow magically got my ac compressor to start kicking on and i think the system is charged. I have 45psi at the fitting above the fan. (low pressure side?)

Still no cool air. The compressor is definitely doing something because i can feel it when i kick it on and off going down the highway.

Sooo, if the system is charged and holding, the ac compressor is working and the fan is blowing into the cabin... what else could be the hold up?

Remove everything on there, and remove the Y vac tube that is locate near the injector pump and connect the other 2 lines together

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Current Garage
2008 Mercedes GL320 CDI 188k mi Repair/Work in progress
1994 S350 160k mi Garage Queen & prepping for repairs
2005 E320 CDI 203k mi Healthy & Daily Driver
1994 S350 357k mi Retried as parts car
1984 300TD 214k mi Blown OM617 Poss OM603 Swap??

Sold
1987 300SDL 200K+
1994 S320 181K mi
2008 E320 Bluetec 127k mi
1999 S420 130K mi
1980 240D 360k mi
15+ Others that has come, stay and gone

GONE, BUT NOT FORGOTTEN
1995 E320 SE 220k mi
1984 300SD 350k mi